All Small Six Oil pressure question

[motopsycha]

I'm working to get my 66 Mustang back on the road after a lot of work this winter. I did a T5 swap along with a cowl replacement and a lot of structural repair and enhancement. I took the opportunity to add a mechanical oil pressure guage to get a better handle on what was happening on the engine front and that is the source of my question.

I am seeing 25-30 psi of oil pressure at idle when up to temp which seems fine but I am not getting any significant rise as rpms increase. Should I be concerned?


details: I did a recent oil change with 20w-50 VR1 and a WIX filter.

 

[aussie7mains]

The ford spec is 35-55psi hot at 2000rpm. There is no spec for idle, which isnt important, just as long as there is some pressure. As to why it isnt rising when the rpm does, possible the relief valve spring is set wrongly or the pump is worn. Also the oil spec for these old engines was 10w-30. Filter brand doesnt matter much they are all pretty much the same, here in Australia we have our own trusted brand "ryco" but these days they are nearly all made in Korea or PRC. Overall if your going to ditch the engine later, then dont worry.

 

[DON]

I think I would go with a 10-30 oil. See what difference it makes. 20-50 is too thick. If it goes too low, you could up it to 10-40.
Make sure it is good and hot. You are boarder line if pressure stays at 30 psi at 2k rpm. That would tell me it’s getting tired on the inside.
Then again, I drove a 67 stang with no oil pressure for yrs until it finally started knocking real bad one morning.
Young and dumb!!!

 

[motopsycha]

Thanks for the replies. At this point I am debating if I should pop the oil pan off and replace the oil pump or just drive it.

 

[sixtseventwo4d]

Whenever your oil pressure is in doubt, attach a different pressure gauge at the port, just to check accuracy. It is the least invasive and easiest way to clear up any questions.

 

[motopsycha]

Whenever your oil pressure is in doubt, attach a different pressure gauge at the port, just to check accuracy. It is the least invasive and easiest way to clear up any questions.

good suggestion. this should be a quick and easy check

 

[motopsycha]

I installed another mechanical gauge right on the block and am seeing similar behavior. The oil pressure sits right around 28 psi. It will increase a little to 30 psi when rpm’s increase but looks to hit that value early and not go higher. It did not change noticeably when the engine was up to temp after a drive.